second/fs_ext2.c

/*
 *  fs_ext2.c - an implementation for the Ext2/Ext3 filesystem
 *
 *  Copyright (C) 2001, 2002 Ethan Benson
 *
 *  Copyright (C) 1999 Benjamin Herrenschmidt
 *
 *  Adapted from quik/silo
 *
 *  Copyright (C) 1996 Maurizio Plaza
 *                1996 Jakub Jelinek
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "ctype.h"
#include "types.h"
#include "stddef.h"
#include "file.h"
#include "prom.h"
#include "string.h"
#include "partition.h"
#include "fs.h"
#include "errors.h"
#include "debug.h"

#define FAST_VERSION
#define MAX_READ_RANGE	256
#undef VERBOSE_DEBUG

typedef int FILE;
#include "linux/ext2_fs.h"
#include "ext2fs/ext2fs.h"

static int ext2_open(	struct boot_file_t*	file,
			const char*		dev_name,
			struct partition_t*	part,
			const char*		file_name);
static int ext2_read(	struct boot_file_t*	file,
			unsigned int		size,
			void*			buffer);
static int ext2_seek(	struct boot_file_t*	file,
			unsigned int		newpos);
static int ext2_close(	struct boot_file_t*	file);

struct fs_t ext2_filesystem =
{
     "ext2",
     ext2_open,
     ext2_read,
     ext2_seek,
     ext2_close
};

/* IO manager structure for the ext2 library */

static errcode_t linux_open (const char *name, int flags, io_channel * channel);
static errcode_t linux_close (io_channel channel);
static errcode_t linux_set_blksize (io_channel channel, int blksize);
static errcode_t linux_read_blk (io_channel channel, unsigned long block, int count, void *data);
static errcode_t linux_write_blk (io_channel channel, unsigned long block, int count, const void *data);
static errcode_t linux_flush (io_channel channel);

static struct struct_io_manager struct_linux_manager =
{
     EXT2_ET_MAGIC_IO_MANAGER,
     "linux I/O Manager",
     linux_open,
     linux_close,
     linux_set_blksize,
     linux_read_blk,
     linux_write_blk,
     linux_flush
};

static io_manager linux_io_manager = &struct_linux_manager;

/* Currently, we have a mess between what is in the file structure
 * and what is stored globally here. I'll clean this up later
 */
static int opened = 0;		/* We can't open twice ! */
static unsigned int bs;		/* Blocksize */
static unsigned long long doff;	/* Byte offset where partition starts */
static ino_t root,cwd;
static ext2_filsys fs = 0;
static struct boot_file_t* cur_file;
static char *block_buffer = NULL;

#ifdef FAST_VERSION
static unsigned long read_range_start;
static unsigned long read_range_count;
static unsigned long read_last_logical;
static unsigned long read_total;
static unsigned long read_max;
static struct boot_file_t* read_cur_file;
static errcode_t read_result;
static char* read_buffer;

static int read_dump_range(void);
static int read_iterator(ext2_filsys fs, blk_t *blocknr, int lg_block, void *private);
#else /* FAST_VERSION */
static struct ext2_inode cur_inode;
#endif /* FAST_VERSION */

void com_err (const char *a, long i, const char *fmt,...)
{
     prom_printf ((char *) fmt);
}

static int
ext2_open(	struct boot_file_t*	file,
		const char*		dev_name,
		struct partition_t*	part,
		const char*		file_name)
{
     int result = 0;
     int error = FILE_ERR_NOTFOUND;
     static char buffer[1024];
     int ofopened = 0;

     DEBUG_ENTER;
     DEBUG_OPEN;

     if (opened) {
	  DEBUG_LEAVE(FILE_ERR_FSBUSY);
	  return FILE_ERR_FSBUSY;
     }
     if (file->device_kind != FILE_DEVICE_BLOCK) {
	  DEBUG_LEAVE(FILE_ERR_BADDEV);
	  return FILE_ERR_BADDEV;
     }

     fs = NULL;

     /* We don't care too much about the device block size since we run
      * thru the deblocker. We may have to change that is we plan to be
      * compatible with older versions of OF
      */
     bs = 1024;
     doff = 0;
     if (part)
	  doff = (unsigned long long)(part->part_start) * part->blocksize;
     cur_file = file;


     DEBUG_F("partition offset: %Lu\n", doff);

     /* Open the OF device for the entire disk */
     strncpy(buffer, dev_name, 1020);
     strcat(buffer, ":0");

     DEBUG_F("<%s>\n", buffer);

     file->of_device = prom_open(buffer);

     DEBUG_F("file->of_device = %p\n", file->of_device);

     if (file->of_device == PROM_INVALID_HANDLE) {

	  DEBUG_F("Can't open device %p\n", file->of_device);
	  DEBUG_LEAVE(FILE_IOERR);
	  return FILE_IOERR;
     }
     ofopened = 1;

     /* Open the ext2 filesystem */
     result = ext2fs_open (buffer, EXT2_FLAG_RW, 0, 0, linux_io_manager, &fs);
     if (result) {

	  if(result == EXT2_ET_BAD_MAGIC)
	  {
	       DEBUG_F( "ext2fs_open returned bad magic loading file %p\n",
			file );
	  }
	  else
	  {
	       DEBUG_F( "ext2fs_open error #%d while loading file %s\n",
			result, file_name);
	  }
	  error = FILE_ERR_BAD_FSYS;
	  goto bail;
     }

     /* Allocate the block buffer */
     block_buffer = malloc(fs->blocksize * 2);
     if (!block_buffer) {

	  DEBUG_F("ext2fs: can't alloc block buffer (%d bytes)\n", fs->blocksize * 2);
	  error = FILE_IOERR;
	  goto bail;
     }

     /* Lookup file by pathname */
     root = cwd = EXT2_ROOT_INO;
     result = ext2fs_namei_follow(fs, root, cwd, file_name, &file->inode);
     if (result) {

	  DEBUG_F("ext2fs_namei error #%d while loading file %s\n", result, file_name);
	  if (result == EXT2_ET_SYMLINK_LOOP)
	       error = FILE_ERR_SYMLINK_LOOP;
	  else if (result == EXT2_ET_FILE_NOT_FOUND)
	       error = FILE_ERR_NOTFOUND;
	  else
	       error = FILE_IOERR;
	  goto bail;
     }

#if 0
     result = ext2fs_follow_link(fs, root, cwd,  file->inode, &file->inode);
     if (result) {

	  DEBUG_F("ext2fs_follow_link error #%d while loading file %s\n", result, file_name);
	  error = FILE_ERR_NOTFOUND;
	  goto bail;
     }
#endif

#ifndef FAST_VERSION
     result = ext2fs_read_inode(fs, file->inode, &cur_inode);
     if (result) {

	  DEBUG_F("ext2fs_read_inode error #%d while loading file %s\n", result, file_name);
	  if (result == EXT2_ET_FILE_TOO_BIG)
	       error = FILE_ERR_LENGTH;
	  else if (result == EXT2_ET_LLSEEK_FAILED)
	       error = FILE_CANT_SEEK;
	  else if (result ==  EXT2_ET_FILE_NOT_FOUND)
	       error = FILE_ERR_NOTFOUND;
	  else
	       error = FILE_IOERR;
	  goto bail;
     }
#endif /* FAST_VERSION */
     file->pos = 0;

     opened = 1;
bail:
     if (!opened) {
	  if (fs)
	       ext2fs_close(fs);
	  fs = NULL;
	  if (ofopened)
	       prom_close(file->of_device);
	  if (block_buffer)
	       free(block_buffer);
	  block_buffer = NULL;
	  cur_file = NULL;

	  DEBUG_LEAVE_F(error);
	  return error;
     }

     DEBUG_LEAVE(FILE_ERR_OK);
     return FILE_ERR_OK;
}

#ifdef FAST_VERSION

static int
read_dump_range(void)
{
     int count = read_range_count;
     int size;

#ifdef VERBOSE_DEBUG
     DEBUG_F("   dumping range: start: 0x%x count: 0x%x\n",
	     read_range_count, read_range_start);
#endif
     /* Check if we need to handle a special case for the last block */
     if ((count * bs) > read_max)
	  count--;
     if (count) {
	  size = count * bs;
	  read_result = io_channel_read_blk(fs->io, read_range_start, count, read_buffer);
	  if (read_result)
	       return BLOCK_ABORT;
	  read_buffer += size;
	  read_max -= size;
	  read_total += size;
	  read_cur_file->pos += size;
	  read_range_count -= count;
	  read_range_start += count;
	  read_last_logical += count;
     }
     /* Handle remaining block */
     if (read_max && read_range_count) {
	  read_result = io_channel_read_blk(fs->io, read_range_start, 1, block_buffer);
	  if (read_result)
	       return BLOCK_ABORT;
	  memcpy(read_buffer, block_buffer, read_max);
	  read_cur_file->pos += read_max;
	  read_total += read_max;
	  read_max = 0;
     }
     read_range_count = read_range_start = 0;

     return (read_max == 0) ? BLOCK_ABORT : 0;
}

static int
read_iterator(ext2_filsys fs, blk_t *blocknr, int lg_block, void *private)
{
#ifdef VERBOSE_DEBUG
     DEBUG_F("read_it: p_bloc: 0x%x, l_bloc: 0x%x, f_pos: 0x%x, rng_pos: 0x%x   ",
	     *blocknr, lg_block, read_cur_file->pos, read_last_logical);
#endif
     if (lg_block < 0) {
#ifdef VERBOSE_DEBUG
	  DEBUG_F(" <skip lg>\n");
#endif
	  return 0;
     }

     /* If we have not reached the start block yet, we skip */
     if (lg_block < read_cur_file->pos / bs) {
#ifdef VERBOSE_DEBUG
	  DEBUG_F(" <skip pos>\n");
#endif
	  return 0;
     }

     /* If block is contiguous to current range, just extend range,
      * exit if we pass the remaining bytes count to read
      */
     if (read_range_start && read_range_count < MAX_READ_RANGE
	 && (*blocknr == read_range_start + read_range_count)
	 && (lg_block == read_last_logical + read_range_count)) {
#ifdef VERBOSE_DEBUG
	  DEBUG_F(" block in range\n");
#endif
	  ++read_range_count;
	  return ((read_range_count * bs) >= read_max) ? BLOCK_ABORT : 0;
     }

     /* Range doesn't match. Dump existing range */
     if (read_range_start) {
#ifdef VERBOSE_DEBUG
	  DEBUG_F(" calling dump range \n");
#endif
	  if (read_dump_range())
	       return BLOCK_ABORT;
     }

     /* Here we handle holes in the file */
     if (lg_block && lg_block != read_last_logical) {
	  unsigned long nzero;
#ifdef VERBOSE_DEBUG
	  DEBUG_F(" hole from lg_bloc 0x%x\n", read_last_logical);
#endif
	  if (read_cur_file->pos % bs) {
	       int offset = read_cur_file->pos % bs;
	       int size = bs - offset;
	       if (size > read_max)
		    size = read_max;
	       memset(read_buffer, 0, size);
	       read_max -= size;
	       read_total += size;
	       read_buffer += size;
	       read_cur_file->pos += size;
	       ++read_last_logical;
	       if (read_max == 0)
		    return BLOCK_ABORT;
	  }
	  nzero = (lg_block - read_last_logical) * bs;
	  if (nzero) {
	       if (nzero > read_max)
		    nzero = read_max;
	       memset(read_buffer, 0, nzero);
	       read_max -= nzero;
	       read_total += nzero;
	       read_buffer += nzero;
	       read_cur_file->pos += nzero;
	       if (read_max == 0)
		    return BLOCK_ABORT;
	  }
	  read_last_logical = lg_block;
     }

     /* If we are not aligned, handle that case */
     if (read_cur_file->pos % bs) {
	  int offset = read_cur_file->pos % bs;
	  int size = bs - offset;
#ifdef VERBOSE_DEBUG
	  DEBUG_F(" handle unaligned start\n");
#endif
	  read_result = io_channel_read_blk(fs->io, *blocknr, 1, block_buffer);
	  if (read_result)
	       return BLOCK_ABORT;
	  if (size > read_max)
	       size = read_max;
	  memcpy(read_buffer, block_buffer + offset, size);
	  read_cur_file->pos += size;
	  read_max -= size;
	  read_total += size;
	  read_buffer += size;
	  read_last_logical = lg_block + 1;
	  return (read_max == 0) ? BLOCK_ABORT : 0;
     }

     /* If there is still a physical block to add, then create a new range */
     if (*blocknr) {
#ifdef VERBOSE_DEBUG
	  DEBUG_F(" new range\n");
#endif
	  read_range_start = *blocknr;
	  read_range_count = 1;
	  return (bs >= read_max) ? BLOCK_ABORT : 0;
     }

#ifdef VERBOSE_DEBUG
     DEBUG_F("\n");
#endif
     return 0;
}

#endif /* FAST_VERSION */

static int
ext2_read(	struct boot_file_t*	file,
		unsigned int		size,
		void*			buffer)
{
     errcode_t retval;

#ifdef FAST_VERSION
     if (!opened)
	  return FILE_IOERR;


     DEBUG_F("ext_read() from pos 0x%Lx, size: 0x%ux\n", file->pos, size);


     read_cur_file = file;
     read_range_start = 0;
     read_range_count = 0;
     read_last_logical = file->pos / bs;
     read_total = 0;
     read_max = size;
     read_buffer = (unsigned char*)buffer;
     read_result = 0;

     retval = ext2fs_block_iterate(fs, file->inode, 0, 0, read_iterator, 0);
     if (retval == BLOCK_ABORT)
	  retval = read_result;
     if (!retval && read_range_start) {
#ifdef VERBOSE_DEBUG
	  DEBUG_F("on exit: range_start is 0x%x, calling dump...\n",
		  read_range_start);
#endif
	  read_dump_range();
	  retval = read_result;
     }
     if (retval)
	  prom_printf ("ext2: i/o error %ld in read\n", (long) retval);

     return read_total;

#else /* FAST_VERSION */
     int status;
     unsigned int read = 0;

     if (!opened)
	  return FILE_IOERR;


     DEBUG_F("ext_read() from pos 0x%x, size: 0x%x\n", file->pos, size);


     while(size) {
	  blk_t fblock = file->pos / bs;
	  blk_t pblock;
	  unsigned int blkorig, s, b;

	  pblock = 0;
	  status = ext2fs_bmap(fs, file->inode, &cur_inode,
			       block_buffer, 0, fblock, &pblock);
	  if (status) {

	       DEBUG_F("ext2fs_bmap(fblock:%d) return: %d\n", fblock, status);
	       return read;
	  }
	  blkorig = fblock * bs;
	  b = file->pos - blkorig;
	  s = ((bs - b) > size) ? size : (bs - b);
	  if (pblock) {
	       unsigned long long pos =
		    ((unsigned long long)pblock) * (unsigned long long)bs;
	       pos += doff;
	       prom_lseek(file->of_device, pos);
	       status = prom_read(file->of_device, block_buffer, bs);
	       if (status != bs) {
		    prom_printf("ext2: io error in read, ex: %d, got: %d\n",
				bs, status);
		    return read;
	       }
	  } else
	       memset(block_buffer, 0, bs);

	  memcpy(buffer, block_buffer + b, s);
	  read += s;
	  size -= s;
	  buffer += s;
	  file->pos += s;
     }
     return read;
#endif /* FAST_VERSION */
}

static int
ext2_seek(	struct boot_file_t*	file,
		unsigned int		newpos)
{
     if (!opened)
	  return FILE_CANT_SEEK;

     file->pos = newpos;
     return FILE_ERR_OK;
}

static int
ext2_close(	struct boot_file_t*	file)
{
     if (!opened)
	  return FILE_IOERR;

     if (block_buffer)
	  free(block_buffer);
     block_buffer = NULL;

     if (fs)
	  ext2fs_close(fs);
     fs = NULL;

     prom_close(file->of_device);
     DEBUG_F("ext2_close called\n");

     opened = 0;

     return 0;
}

static errcode_t linux_open (const char *name, int flags, io_channel * channel)
{
     io_channel io;


     if (!name)
	  return EXT2_ET_BAD_DEVICE_NAME;
     io = (io_channel) malloc (sizeof (struct struct_io_channel));
     if (!io)
	  return EXT2_ET_BAD_DEVICE_NAME;
     memset (io, 0, sizeof (struct struct_io_channel));
     io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
     io->manager = linux_io_manager;
     io->name = (char *) malloc (strlen (name) + 1);
     strcpy (io->name, name);
     io->block_size = bs;
     io->read_error = 0;
     io->write_error = 0;
     *channel = io;

     return 0;
}

static errcode_t linux_close (io_channel channel)
{
     free(channel);
     return 0;
}

static errcode_t linux_set_blksize (io_channel channel, int blksize)
{
     channel->block_size = bs = blksize;
     if (block_buffer) {
	  free(block_buffer);
	  block_buffer = malloc(bs * 2);
     }
     return 0;
}

static errcode_t linux_read_blk (io_channel channel, unsigned long block, int count, void *data)
{
     int size;
     unsigned long long tempb;

     if (count == 0)
	  return 0;

     tempb = (((unsigned long long) block) *
	      ((unsigned long long)bs)) + (unsigned long long)doff;
     size = (count < 0) ? -count : count * bs;
     prom_lseek(cur_file->of_device, tempb);
     if (prom_read(cur_file->of_device, data, size) != size) {
	  DEBUG_F("\nRead error on block %ld\n", block);
	  return EXT2_ET_SHORT_READ;
     }
     return 0;
}

static errcode_t linux_write_blk (io_channel channel, unsigned long block, int count, const void *data)
{
     return 0;
}

static errcode_t linux_flush (io_channel channel)
{
     return 0;
}

/*
 * Local variables:
 * c-file-style: "k&r"
 * c-basic-offset: 5
 * End:
 */